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High-performance long-wavelength InAs/GaSb superlattice detectors grown by MOCVD
摘要： We demonstrate high-performance long-wavelength InAs/GaSb superlattice (SL) infrared photodetectors based on an Al-free single heterojunction grown by metalorganic chemical vapor deposition (MOCVD). The device structure consists of a mid-wavelength InAs/GaSb SL p-n junction (PN) and a long-wavelength InAs/GaSb SL n-type absorber (n), so-called PNn design, to reduce the dark current. In addition, a shallow etch technique was employed by exposing only mid-wavelength materials during pixel isolation to suppress surface leakage currents. At 77 K and a bias voltage of -0.1 V, the device exhibited a 50% cut-off wavelength at 8.0 μm, a dark current density of 2.4×10-5 A/cm2, and a peak responsivity of 2.1 A/W. Temperature dependent dark current measurement indicated diffusion-limited behavior down to 75 K. The specific detectivity was estimated to be 7.3×1011 cm·Hz1/2/W, which is comparable with that of detectors grown by molecular beam epitaxy (MBE) at similar cut-off wavelengths.
关键词： InAs/GaSb type-II superlattices,metalorganic chemical vapor deposition,heterostructure,long-wavelength infrared
更新于2025-09-23 15:22:29
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Ultrabroadband Photodetectors up to 10.6 ?μm Based on 2D Fe <sub/>3</sub> O <sub/>4</sub> Nanosheets
摘要： The ultrabroadband spectrum detection from ultraviolet (UV) to long-wavelength infrared (LWIR) is promising for diversified optoelectronic applications of imaging, sensing, and communication. However, the current LWIR-detecting devices suffer from low photoresponsivity, high cost, and cryogenic environment. Herein, a high-performance ultrabroadband photodetector is demonstrated with detecting range from UV to LWIR based on air-stable non-layered ultrathin Fe3O4 nanosheets synthesized via a space-confined chemical vapor deposition (CVD) method. Ultrahigh photoresponsivity (R) of 561.2 A W?1, external quantum efficiency (EQE) of 6.6 × 103%, and detectivity (D*) of 7.42 × 108 Jones are achieved at the wavelength of 10.6 μm. The multi-mechanism synergistic effect of photoconductive effect and bolometric effect demonstrates the high sensitivity for light with any light intensities. The outstanding device performance and complementary mixing photo response mechanisms open up new potential applications of nonlayered 2D materials for future infrared optoelectronic devices.
关键词： long-wavelength infrared,photoconductive effect,ultrabroadband photodetectors,bolometric effect,Fe3O4 nanosheets
更新于2025-09-23 15:21:01
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Carrier reduction studies of type-II superlattice materials for very long wavelength infrared sensing
摘要： There are continuing efforts to develop type-II superlattice (SL) materials for very long wavelength infrared (VLWIR) detector applications. However, the SLs have high residual electron background doping densities that depend on SL growth conditions, which lead to shorter minority carrier lifetime and lower performance parameters than theoretically predicted. In this study, the authors compare the technical advantages of using InAs/GaInSb over InAs/GaSb SL with respect to reducing the electron doping levels. Our temperature-dependent electrical transport measurements show that the InAs/GaInSb SL design has a lower electron density than the InAs/GaSb SL with the same bandgap and have electron densities (mobilities) on the order of the mid 1011 cm?2 (25 000 cm2/V s). Since small period InAs/GaInSb SLs also produce greater Auger recombination suppression for a given VLWIR gap than the large period InAs/GaSb SL, the InAs/GaInSb SL appears to be a better candidate for long lifetime IR materials for future very long wavelength infrared devices.
关键词： very long wavelength infrared,mobility,InAs/GaSb,Auger recombination,InAs/GaInSb,type-II superlattice,carrier reduction,electron doping
更新于2025-09-19 17:15:36
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Long Wavelength Infrared Quantum Cascade Detector
摘要： The effect of the barrier width in the photovoltaic-type quantum cascade detector structure on the responsivity and the zero-bias resistance of the device are opposite. A wide barrier can increase the zero-bias resistance but hinder the transport of photo-generated carriers and decrease the responsivity. The design of a long wave infrared cascade detector usually focuses on increasing the zero bias resistance by using wide barriers to lower the thermal noise, but the photocurrent might be low in this case. Even though the thermal noise that dominates the noise performance of a photovoltaic quantum cascade detector is very low, it is possible that effective photoresponse signals cannot be obtained when the photocurrent is as low as the noise current of measurement circuits, which might be higher than the thermal noise of the detector itself. In this work, we modified the structure of our previous long wavelength infrared quantum cascade detector by increasing the number of cascaded stages, while reducing the barrier thickness to improve the responsivity of the device. Although the device’s zero bias resistance decreases due to thinning of the barrier, the detectivity is almost unaffected due to the significant increase in response. More importantly, the operating temperature of the device is increased. Therefore, optimization of long wave infrared QCDs should consider both the resistance and the photocurrent flow.
关键词： Quantum Cascade Photodetector,Long Wavelength Infrared
更新于2025-09-04 15:30:14